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Box Tunnel
Box Tunnel passes through Box Hill on the Great Western Main Line (GWML) between Bath and Chippenham. The 1.83-mile (2.95 km) tunnel was the world's longest railway tunnel when it was completed in 1841.
Built between December 1838 and June 1841 for the Great Western Railway (GWR) under the direction of Isambard Kingdom Brunel, the straight tunnel descends on a 1 in 100 gradient from its eastern end. At the time the tunnel's construction was considered dangerous due to its length and the composition of the underlying strata. The west portal is Grade II* listed and the east portal is Grade II listed.
Ammunition was stored near the tunnel during World War II, reusing mine workings. During the 2010s, the tunnel was modified and the track lowered to prepare it for electrification, although in 2016, this plan was suspended.
During the 1830s, Isambard Kingdom Brunel developed a plan for a railway running east–west between London and Bristol. The Great Western Main Line would maintain either level ground or gentle gradients of no greater than 1 in 1000 along most of its route. Between Swindon and Bath, at the highest point of the line, a tunnel was proposed through Box Hill, outside Corsham.
The tunnel would have a gradient of 1 in 100. At the time, the use of such a steep gradient inside the tunnel allegedly provoked criticism by some of Brunel's contemporaries. Box Tunnel would be the longest railway tunnel at almost 1+3⁄4 miles (2.8 km) in length.
While a tunnel had been included in the 1835 Great Western Railway Act, contemporary engineers considered the construction of Box Tunnel to be an impossibility at worst and a dangerous undertaking at best. The challenge posed was not only its length but the difficult underlying strata it would have to pass through. The rocks through which it passes comprise Great Oolite overlying fuller's earth, and Inferior Oolite and Bridport Sand beneath, a combination with which tunnellers were familiar.
The Great Oolite limestone, known as Bath Stone, is easily worked and had been used for construction since Roman times. In the 17th and 18th centuries it was extracted by the room and pillar method and used for many buildings in Bath, Somerset. To assess the geology more accurately, between 1836 and 1837, Brunel sank eight shafts at intervals along the tunnel's projected alignment.
The GWR selected George Burge of Herne Bay as the major contractor, being responsible for undertaking 75 per cent of overall tunnel length, working from the western end. Burge appointed Samuel Yockney as his engineer and manager. Locally based Lewis and Brewer were responsible for the remainder, starting from the eastern side. One of Brunel's personal assistants, William Glennie, was in overall charge until completion.
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Box Tunnel
Box Tunnel passes through Box Hill on the Great Western Main Line (GWML) between Bath and Chippenham. The 1.83-mile (2.95 km) tunnel was the world's longest railway tunnel when it was completed in 1841.
Built between December 1838 and June 1841 for the Great Western Railway (GWR) under the direction of Isambard Kingdom Brunel, the straight tunnel descends on a 1 in 100 gradient from its eastern end. At the time the tunnel's construction was considered dangerous due to its length and the composition of the underlying strata. The west portal is Grade II* listed and the east portal is Grade II listed.
Ammunition was stored near the tunnel during World War II, reusing mine workings. During the 2010s, the tunnel was modified and the track lowered to prepare it for electrification, although in 2016, this plan was suspended.
During the 1830s, Isambard Kingdom Brunel developed a plan for a railway running east–west between London and Bristol. The Great Western Main Line would maintain either level ground or gentle gradients of no greater than 1 in 1000 along most of its route. Between Swindon and Bath, at the highest point of the line, a tunnel was proposed through Box Hill, outside Corsham.
The tunnel would have a gradient of 1 in 100. At the time, the use of such a steep gradient inside the tunnel allegedly provoked criticism by some of Brunel's contemporaries. Box Tunnel would be the longest railway tunnel at almost 1+3⁄4 miles (2.8 km) in length.
While a tunnel had been included in the 1835 Great Western Railway Act, contemporary engineers considered the construction of Box Tunnel to be an impossibility at worst and a dangerous undertaking at best. The challenge posed was not only its length but the difficult underlying strata it would have to pass through. The rocks through which it passes comprise Great Oolite overlying fuller's earth, and Inferior Oolite and Bridport Sand beneath, a combination with which tunnellers were familiar.
The Great Oolite limestone, known as Bath Stone, is easily worked and had been used for construction since Roman times. In the 17th and 18th centuries it was extracted by the room and pillar method and used for many buildings in Bath, Somerset. To assess the geology more accurately, between 1836 and 1837, Brunel sank eight shafts at intervals along the tunnel's projected alignment.
The GWR selected George Burge of Herne Bay as the major contractor, being responsible for undertaking 75 per cent of overall tunnel length, working from the western end. Burge appointed Samuel Yockney as his engineer and manager. Locally based Lewis and Brewer were responsible for the remainder, starting from the eastern side. One of Brunel's personal assistants, William Glennie, was in overall charge until completion.